Heating and cooling apparatus



Nov. 1 7, 1959 W. L. MOGRATH HEATING AND COOLING APPARATUS Filed Jan. l0, 1958 POWER 8i CAPACITY OUTSIDE FIG.I

INVENTOR. WILLIAM L. Mc GRATH- United Se@ Patent@ This invention relates to air conditioning apparatus'. More particularly this inventionfrlates'to air conditioning equipment' embodying'a refrigeration"l system which may be selectively operated Vtor'laeatfandpe'iol an enclosure. A f' f 'I While the invention. isprimarily useful with a refrigeration system operable under the well known yreverse cycle principle commonly called heat pumpsit` may also `be. used with air conditioning equipment"wherev flow of refrigerant through the refrigerationy `system is not reversed but where the ow paths ofthe lmedia-owingover the heat transfer coils in the system are manipulated by suitablewdampers, to create `a cooling or heatingn effectv to the medium being suppliedfto the enclosure-served by the equipment. 'i v* 'Heat,pumps, as apparatus of this general type has been commonly known, have not been Itoo widely'used in geographical areas such as the northern-parts "of the UnitedStates where relatively low ambient temperatures are-encountered during the winter seasonL when the'requirement for heating is` greatest; Efforts to overcome the lproblem or" "supplying"A additional heat' to an er1.- closure have resulted in utilization of supplementary heating means such as' strip heaters'which, in effect, operate as resistance heating elements. "I" f'" During the season of the yearwhe'nitV is required 'that the heat pump vsupply to "the enclosure being'served,a supply of heat suicient to satisfy the loadenthe house it has been found that apparatus designed to satisfythe cooling load on the enclosure often'is incapable of providing -or satisfying the heating load on ythe j enclosure. This is true primarily because of the additional, temperature lift required to provide comfortablev ondit'ions within the enclosure during the'heating seasonf i Also conventional heat pumps of the kind under consideration are able to, -use'onlya` 'smallj part of the total'elec'trical capacity or supply' available at the source ICC,

2 A. This invention has for another objectvv the provision of a heat pump vequipped*with 'a compressonthe output of which may be -varied during `the heating vseason/when the ambient-temperatures encountered reach a predetermined low value. Thus the compressor has the inherentpoten'- tial of satisfying both thef'heating loadk and rthe cooling load despite the fact that substantial diiferences' in ,thev

-degree of performanceiduring the tWo'seasonsare v-involved'. y

Another object of this Viivention involves @an arrangement for the compressor of "a heat pumpl which will'permit increased cooling lto be obtained du' ing operation of 'the heat pump on the colingcyclefy 'f V vIn attaining the objects of this invention; a heat pump' is :Provided wherein the compressor `is provided with means for varyingthe clearance 'of at least 'one' k'cylinder in order' toregulatef'or controlt'he `volur'netric 'eiciency j of the compressor. Thus'r'when it isfrequi'red that the' compressor provide a' substantial temperature" liftiffthe apparatus `is automatically operated to fulfill ythis need.

l,Other advantages and objects Y'of lthis invention will'v'be apparent upon a considerationl of the ensuing- `spe'cific'zati'on and drawings in which:l h .n i j` V Figure lis a diagrammatic view of a heat pump ,convstructed in accordance with thishinventionf Figure 2 is a `graphic representation of the relationships between thepow'erI consumption, system capacity and heatof installation of the heat pump at low outside temperatures when the heating load'is highest. It is therefore a primary object of the invention tofprovide a heat pump that may effectively Vvutilize thevmaximum amount 'of' available electri'eity duriig operation of -the unit at low ambient or outdoor temperatures.

It is a further object of the invention to provide apparatus for heating and cooling `'an-enclosure which includes a heat pump arrangedso that substantially equivalent amounts of electrical power or input areutl'ized when the unit is operating on the cooling cycle 'atfmaxif mum loadt'conditions, on cooling-at rating conditions or on`- heating at low outside'tempera'tures:' -v 7 A still further object of the invention is the provision of a system for heating and cooling a space by means of apparatus operable under the heat pump or reverse cycle principle which will deliver a maximum amount of heat to the space or enclosure under conditions of winter design temperature without exceeding the supplyof electrical current dictated b-y maximum loading conditions on the cooling cycle. v

ing `characteristics'"of a'ic'ohventional heat'pump as they vary with yrespectv to outside temperature; and Figure 3 is a graphical representation of the relationships` shown in Figurelrevised toy illustrate Vthe performanceof the 'heat pump constructed Vin 'accordance with this invention. Referring to Figure 1, a heat *pumpI of the 'typegto which this invention'pertains is illustrated diagrammatically. It will be observed that thesystem illustratedi'is lmore" commonly known'as an air l air-two-piece"heat Compressor-10 ofthe fluid displacement typefor'wards hotgaseous,refrigerant through -dischargeyline` y'11 :toma four way reversingvalve 12;"toan inside ycoil when lthe 'unit' is operating" on the heating'cycle. "The4 gaseous l'refrigerant inthe coil,13 is liquiiied as a'irwithin the enclosure is circulated over the coil through'theyaction of fan '17. Liquid `refrigerant tiowsrthrough capillaryll, or other suitable expansion device,to' an outside coil ISL Here, heat is' extracted from the` ambient air there? frigerant therein vaporized; Ambientair ispdelirvered overtfhe vsurface ofthe coil through thel action of fan 18. Thegaseous refrigerant thenows through *the reversing valve 12, suction line 16, to 'the uid'displacementcom :pressor 1i! to complete the cycle. Y

When itis desired to operate the unit on the cooling cycle, reversing valve 12 is lindexecljthrough a control (notshown) so thatl the hot gaseous refrigerant llowing in line 11 is directed to the coil '18.` From the coilfit' ows through the expansion device 14` to the indoorjcoil 13` where heat is {extracted from the air flowing over then coil,` vaporizing'the refrigerant`.` Vaporous refrigerantthenows through the four Wa valve into line 16 andinto the compressor .10,

. 'R errivg more particularly toy thecompressor 10,

V`,enoted thati.a,piston 1'9 is disposed incylinder 19' f 1i-.111e .'C'QIIPrSS @dit @needed t.orentirely.. to, a crankshaft 20 in the usual conventional manner. Located adjacent the cylinder 19' is chamber 21 having a movable valve or block element 22. The Vmovable element 22 is normally urged under the action of tension spring 23 to the right so as to 'permit a substantial por-` tion of the volume of chamber 21 to be in communication with the cylinder 19'. With the parts arranged in the position described, operation of the unit under the PateefelNP Y1 7 1,259

cooling cycle as well as a substantial part of the heating cycle may be effected.

Lubrication for the moving parts of the compressor is under the influence of a pump 24. A branch line 25 of the lubrication circuit connects with the chamber 21 and flow through the branch line 25 is under the control of valve 26. Normally closed valve 26 is operative in response to mechanism sensing the temperature of the ambient air owing under the in duence of fan 1S over coil 15.

Considering the operation of the heat pump, as indicated above, valve or element 22 assumes its retracted position when the temperature of the air being introduced over the coil is in excess of 30 F. Under these circumstances the valve 22 is in its normally retracted position permitting cylinder 19 to have a relatively large clearance. Under these circumstances, the volumetric eiciency of the compressor is such that the temperature lift under cooling operating conditions may be satised While the compressor inherently is capable of satisfying the relatively steeper temperature lift encountered on the heating cycle. The term temperature lift as employed here refers to the difference between the evaporator temperature and the condensing temperature under a given design cooling condition or under a given design heating condition.

When it is desired to operate the heat pump on the heating cycle, as for example under those circumstances where the ambient temperature may drop below 70 F., the reversing valve 141 is indexed so that gaseous refrigerant is free to tlow from discharge line 11 to the inside coil 13. As long as the ambient temperature is maintained above 30 or any desired outdoor temperature the compressor 10 operates with the same volumetric efficiency as it did on the cooling cycle. It will be appreciated of course that the temperature lift involved is relatively greater as the ambient drops so that the capacity of the compressor decreases.

When the outdoor temperature reaches 30 the unit is operating on the heating cycle, with valve 26 opened, through the action of the thermostatically controlled switch 27, and the bellows 27', permitting oil under pressure in the lubrication circuit of the machine to flow into chamber 21. As the pressure builds up in chamber 21, the block or valve 22 is moved against the action of tension spring 23 to the position shown in Figure l. The cylinder clearance in the machine is now reduced so that the volumetric eiciency of the compressor is increased. This permits the compressor to attain the required lift between the low side and the high side of the system with substantially more capacity. Further the system requirement for heating is more nearly satisfied as will be later apparent.

When the outside air temperature exceeds 30 or any other convenient setting of the thermostat 27, the valve 26 closes, trapping within the chamber and that portion of the branch line 25 between the valve and the chamber, a quantity of oil. However the parts are so proportioned that oil leakage occurs around the valve 22 so that eventualy the valve 22 is retracted under the influence of the spring 23 to its position under cooling cycle operation where the volumetric efficiency of the compressor is lower.

To graphically illustrate the savings involved in utilizing a compressor of the type described, reference is made to Figures 2 and 3. In Figure 2, for example, Curve C represents the capacity of a conventional heat pump wherein the capacity is 100% at code conditions which involve a outside temperature. It will be appreciated that during operation of the unit on the heating cycle, capacity drops to approximately 25% when 0 ambient temperature is reached. The curve C represents the capacity, and curve P the power expended.

Figure 3, however, represents conditions which are obtained by virtue of the invention described above. It will be noted that the capacity curve C is substantially the same as the capacity of curve C with the exception that capacity occurs in the region of 115 ambient temperature as opposed to 95 ambient temperature. This condition reflects the effect of the increased clearance. As indicated above, when the ambient temperature reaches 30, the volumetric eiciency of the compressor is increased as the clearance in the cylinder is decreased. Thus as the greater weight of refrigerant is pumped by the compressor, due to the decreased cylinder clearance, a greater volume of refrigerant at a relatively high temperature is presented to the indoor coil for liquication and extraction of heat. Thus it will be appreciated that the capacity rises in accordance with the horizontal portion of the curve at the 30 ambient temperature line of the curve represented in Figure 3. Further, with reference to the graph illustrated in Figure 3, it will be noted that the heat requirements of the system as indicated by the curve H are more nearly balanced with respect to the capacity of the heat pump and the power in the supply located at the installation of the unit is more eifectively utilized. This reduces the necessity for the use of supplementary heating means such as the resistance heaters mentioned above.

Although the embodiment selected to illustrate the invention includes the arrangement for varying the compressor clearance illustrated in Figure 1, it will be apparent that other devices designed to perform this function may be used, if desired.

While I have described preferred embodiments of the invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims:

I claim:

1. In apparatus for heating and cooling an enclosure, a refrigeration system comprising a compressor having at least one cylinder with a piston member therein, and a lubrication system, a first heat transfer coil located within the enclosure and a second heat transfer coil located outside the enclosure, connected to form a circuit for the ow of refrigerant, means for automatically adjusting the clearance in said compressor to vary the volumetric efficiency of the compressor, said means including a chamber in communication with said cylinder, a piston slidable in said chamber, spring means attached to said piston, a conduit connecting the compressor with the chamber for delivering lubricant to the chamber to oppose the action of said spring and regulating valve means in said conduit.

2. The invention set forth in claim l wherein valve means is operable in response to the temperature of the medium flowing over said outdoor coil.

References Cited in the file of this patent UNITED STATES PATENTS 2,761,615 Prince Sept. 4, 1956 2,785,540 Biehn Mar. 19, 1957 2,833,462 Scheerer May 6, 1958 

